Surface reaction process at epitaxial growth of 3C-SiC on Si(001) using organosilicon compounds

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The objective of this project is to understand the reaction processes during the epitaxial growth of 3C-SiC on Si(001) substrates using organosilicon compounds as source materials in order to realize the low temperature epitaxial growth of SiC with excellent properties.In 2002, the initial reaction process of dimethylsilane(DMS) or monomechylsilane(MMS) on Si (2x1) surface was observed in-situ using reflection high-energy electron diffraction(RHEED) and scanning tunneling microscopy(STM) : On the surface of Si c(4x4) structure, which appears in RHEED pattern during incubation time before SiC nucleation, both Si(2x1) and Si c(4x4) structures were observed by STM measurement. From the evaluation of the lattice constant for the both structures by lineprofile measurement, the c(4x4) domain was contracted and the Si(2x1) domain was expanded. SiC islands were not nucleated along atomic steps of the substrate surface but on the terrace. In addition, the SiC islands were grown along <100> azimuth from AFM measurement. This direction agrees with that the positions of carbon atoms diffused into subsurface layer of c(4x4). From these results, it was considered that the SiC islands were formed on the c(4x4) domain.In 2003, radicals and molecules desorbed from the reaction surface were identified using a quadrupole mass spectrometer. Methyl and silyl groups were hardly detected, and hydrogen molecules were only detected during the reaction between MMS(DMS) and Si(2x1) surface. From these results, methyl and silyl groups do not desorb from the surface but decompose into C and Si atoms. The C atoms diffuse into the substrate and the Si atoms compensate dimer vacancies during the formation of c(4x4) structure, and both atoms are incorporated into SiC islands during film growth. From temperature-programmed desorption spectra using the mass spectrometer, the formation of Si-C bonds in the back bonds of Si double occupied dimers(DOD) was confirmed on the c(4x4) surface.